This proposal describes plans to develop a user-friendly interactive statistical software package to perform dose response modeling and quantitative risk assessment. Cancer and non-cancer applications in a variety of standard and non-standard contexts will be covered. Phase I focuses on software to fit multivariate dose response models to developmental toxicity data. Specifically, the approach involves a three- stage model that accounts for exposure effects on fetal death, malformation and weight. The software will provide for: (l) the fitting of non-linear dose response models to clustered binary and continuous data; (2) graphical displays to facilitate assessment of model adequacy; and (3) estimation of Benchmark Doses (or, the doses corresponding to specific risk quantiles) based on multiple outcomes. These features will be accessible in an interactive, menu-based user-interface that facilitates data exploration and sensitivity analyses. Achievement of these Phase I goals will lead naturally to the long term goals (Phase II) of providing a cohesive and flexible package that accommodates risk assessment needs in virtually all contexts that are likely to be encountered in practice, including carcinogen bioassays, neurotoxicity testing.